Biodiesel is a non-toxic and biodegradable fuel that is made from vegetable oils, waste cooking oil, animal fats or tall oil (a by-product from pulp and paper processing). Biodiesel is produced from these feedstocks through a process called transesterification, by reacting the oil with an alcohol (usually methanol, although ethanol can also be used) and a catalyst (such as sodium hydroxide). The resulting chemical reaction produces glycerine and an ester called biodiesel. The majority of biodiesel is produced by this method.
Compared with conventional diesel, biodiesel combusts better with a higher cetane rating and produces fewer life cycle greenhouse gas emissions (GHG) which contribute to climate change.
Biodiesel blends, a mixture of petroleum diesel and biodiesel, can be used in any diesel engine. As biodiesel can be blended with diesel in any concentration, the blend level depends on economics, availability, the desired emissions level, material compatibility and combustion characteristics. An increasing number of Original Equipment Manufacturers are endorsing the use of lower biodiesel blends, e.g, 5% in their engines. Some manufacturers now extend warranty coverage for new diesel powered vehicles to use lower blends of biodiesel, provided the fuel meets applicable standards. Some manufacturers also provide vehicles pre-filled with biodiesel blends.
In colder climates, biodiesel tends to lose viscosity, particularly at higher blend levels. To counter this effect, changes to the feedstock source or additives may be needed to address the cold flow properties of this fuel. Research and testing is underway to reduce biodiesel production costs and address cold weather problems.
Toronto Hydro fleet vehicles are currently using biodiesel concentrations of 5 percent (B-5) and 20 percent (B-20). Saskatoon Transit Services and Société de transport de Montréal (STM) are also testing B-5 and B-20 in city buses.
Tailpipe GHG emissions are only very slightly lower using biodiesel over petrodiesel, however, over the life cycle – from growing oilseeds or collecting rendering animal waste through fuel production and use – pure biodiesel produces 60 to 100 percent fewer greenhouse gas emissions compared with petroleum diesel, depending on what oil or fat is used to make it. A 20 percent blend of biodiesel with petroleum diesel (B-20) produces 12 to 18 percent fewer emissions, and a 2 percent blend (B-2) produces 1 to 2 percent fewer emissions. As well, by converting certain waste products into biodiesel, they are diverted from landfill sites where they may have produced methane gas, which contributes to climate change.
Biodiesel itself is composed of 11 percent oxygen by mass and is almost sulphur-free, thus even low concentrations added to petroleum diesel make it burn better and may improve the performance of catalytic converters.
Biodiesel can be produced from local, renewable resources – either agricultural products or agro-industry residues such as slaughterhouse waste, recycled cooking oil, non-food-grade virgin oil or agricultural surplus. This can provide new value for products that were once destined for a landfill site, creating new markets for local industries and reducing government's and industry's disposal costs.
Most North American vehicle engine manufacturers generally warranty up to a B5 level. Warranty coverage up to a B20 level is offered by select manufacturers under specific conditions.
The Engine Manufacturers Association has issued a technical statement indicating a 5 percent biodiesel blend (B5) should not cause engine or fuel systems problems. A number of automobile manufacturers also endorse lower biodiesel blends for use in their vehicles. As biodiesel is more widely tested and used, manufacturers will be in a better position to support the use of higher blends.
Biodiesel is considerably less flammable than petroleum diesel, which burns at 50°C (120°F). Pure biodiesel (B-100) does not ignite until 150°C (300°F). The flashpoint (the temperature at which it will ignite when exposed to a spark or flame) of a biodiesel blend falls somewhere between these temperatures, depending on the mixture.
Because biodiesel is a mild solvent it is important to wipe up spills and dispose of rags safely. Biodiesel may deface some paints if left on painted surfaces for a long time.
Biodiesel-powered engines have been shown to deliver similar torque and horsepower as diesel-powered engines. Biodiesel has a higher cetane rating, which can improve engine performance. Biodiesel contains only slightly less energy per litre than on-road petrodiesel.
The Engine Manufacturers Association has issued a technical statement indicating a 5 percent biodiesel blend (B5) should not cause engine or fuel systems problems. A number of automobile manufacturers also endorse lower biodiesel blends for use in their vehicles. As biodiesel is more widely tested and used, manufacturers will be in a better position to support the use of higher blends.
Like petroleum diesel, biodiesel can gel in cold weather. Laboratory tests show that a biodiesel blend gels at a higher temperature than petroleum diesel. Actual experience with cold weather operations varies across regions and is influenced by many factors including the type of feedstock used. B20 has been tested in buses in Montréal, Saskatoon, Halifax, and Toronto Hydro fleets.
Some types of biodiesel freeze at lower temperatures than others, depending on the feedstock and characteristics of the fuel. Potential solutions to cold weather problems are similar to those for petroleum diesel. They include using fuel additives and engine block or fuel filter heaters and storing vehicles near or in a building.
It is important to clean storage tanks before using higher blends of biodiesel because biodiesel acts as a mild solvent. This characteristic makes it "clean out" sediments and dirt from fuel tanks and storage systems. If high blends are put into aged and dirty systems that previously held petroleum diesel, biodiesel will dissolve the sediments and carry them into vehicle fuel systems. In most cases, more frequent fuel filter changes will suffice until the fuel storage tanks and associated equipment have been cleaned out. In severe cases, the dissolved sediments can cause fuel injector failure.
Biodiesel is being tested with some vehicle fleets, but it is not yet widely commercially available in Canada, except for a few retail sites in Ontario and British Columbia.
Toronto Hydro fleet vehicles are currently using biodiesel concentrations of 5 percent (B-5) and 20 percent (B-20). Saskatoon Transit Services and Société de transport de Montréal (STM) are also testing B-5 and B-20 in city buses. Technological advances in biodiesel production may reduce its costs.
Because biodiesel is available in liquid form, similar to petroleum diesel, vehicles are refuelled in the same manner.